Give the gate a short changed list as an argument, as before, so an older judge still runs (issue 1247, review round 1)

internal/builder/check_changed_test.go

@@ -81,15 +81,36 @@ func TestAShortListOfChangedPathsStaysAsItWasAndIsInTheFileToo(t *testing.T) { /
 	}
 }
 
-func TestTheGateReadsTheChangedPathsFromTheFile(t *testing.T) { // 1247/AC3
+// theGatesCommand is the command gateLayer hands the toolchain for the merge gate, given the environment of the check.
+func theGatesCommand(t *testing.T, env []string) string {
+	t.Helper()
 	var args []string
-	gateLayer(t.Context(), CheckSpec{}, t.TempDir(), t.TempDir(), "gate", filepath.Join(t.TempDir(), "verdict.json"), nil,
+	gateLayer(t.Context(), CheckSpec{}, t.TempDir(), t.TempDir(), "gate", filepath.Join(t.TempDir(), "verdict.json"), env,
 		func(dir string, env []string, command ...string) []string { return command },
 		func(a []string) error { args = a; return errors.New("stop here") }, &tail{}, "bus", "name", false, "", nil,
 		func(string, string, ...any) {})
-	command := strings.Join(args, " ")
+	return strings.Join(args, " ")
+}
+
+func TestTheGateIsGivenAShortListAsBeforeSoAnOlderJudgeStillRuns(t *testing.T) { // 1247/AC3
+	env, err := changedEnvironment(t.TempDir(), []string{"a.go", "b.go"}, func(string) {})
+	if err != nil {
+		t.Fatal(err)
+	}
+	command := theGatesCommand(t, env)
+	if !strings.Contains(command, `--changed "$MESH_CHECK_CHANGED"`) || strings.Contains(command, "--changed-file") {
+		t.Errorf("a short list is not given to the gate as --changed alone: %s", command)
+	}
+}
+
+func TestTheGateReadsACutListFromTheFile(t *testing.T) { // 1247/AC3
+	env, err := changedEnvironment(t.TempDir(), manyPaths(), func(string) {})
+	if err != nil {
+		t.Fatal(err)
+	}
+	command := theGatesCommand(t, env)
 	if !strings.Contains(command, `--changed-file "$MESH_CHECK_CHANGED_FILE"`) || strings.Contains(command, `--changed "`) {
-		t.Errorf("the gate's command does not read the paths from the file: %s", command)
+		t.Errorf("a cut list is not given to the gate through the file alone: %s", command)
 	}
 }